apr_thread: destroy the thread's pool at _join() time, unless _detach()ed.

Destroying a joinable thread pool from apr_thread_exit() or when the thread
function returns, i.e. from inside the thread itself, is racy or deadlocky
with APR_POOL_DEBUG, with the parent pool being destroyed.

This commit adds a ->detached flag in each arch's apr_thread_t struct to track
whether a thread is detached (either at _create() or _detach() time). If
detached, the pool is destroyed when the thread exits, otherwise when the
thread is joined with apr_thread_join().


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@1884077 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 20 insertions, 4 deletions

diff --git a/threadproc/beos/thread.c b/threadproc/beos/thread.c
index c372f135e..61d7fd0d7 100644
--- a/threadproc/beos/thread.c
+++ b/threadproc/beos/thread.c
@@ -69,7 +69,9 @@ static void *dummy_worker(void *opaque)
 
     apr_pool_owner_set(thd->pool, 0);
     ret = thd->func(thd, thd->data);
-    apr_pool_destroy(thd->pool);
+    if (thd->detached) {
+        apr_pool_destroy(thd->pool);
+    }
     return ret;
 }
 
@@ -80,7 +82,7 @@ APR_DECLARE(apr_status_t) apr_thread_create(apr_thread_t **new, apr_threadattr_t
     int32 temp;
     apr_status_t stat;
     
-    (*new) = (apr_thread_t *)apr_palloc(pool, sizeof(apr_thread_t));
+    (*new) = (apr_thread_t *)apr_pcalloc(pool, sizeof(apr_thread_t));
     if ((*new) == NULL) {
         return APR_ENOMEM;
     }
@@ -88,6 +90,7 @@ APR_DECLARE(apr_status_t) apr_thread_create(apr_thread_t **new, apr_threadattr_t
     (*new)->data = data;
     (*new)->func = func;
     (*new)->exitval = -1;
+    (*new)->detached = (attr && apr_threadattr_detach_get(attr) == APR_DETACH);
 
     /* First we create the new thread...*/
 	if (attr)
@@ -126,14 +129,21 @@ int apr_os_thread_equal(apr_os_thread_t tid1, apr_os_thread_t tid2)
 
 APR_DECLARE(void) apr_thread_exit(apr_thread_t *thd, apr_status_t retval)
 {
-    apr_pool_destroy(thd->pool);
     thd->exitval = retval;
+    if (thd->detached) {
+        apr_pool_destroy(thd->pool);
+    }
     exit_thread ((status_t)(retval));
 }
 
 APR_DECLARE(apr_status_t) apr_thread_join(apr_status_t *retval, apr_thread_t *thd)
 {
     status_t rv = 0, ret;
+
+    if (thd->detached) {
+        return APR_EINVAL;
+    }
+
     ret = wait_for_thread(thd->td, &rv);
     if (ret == B_NO_ERROR) {
         *retval = rv;
@@ -145,6 +155,7 @@ APR_DECLARE(apr_status_t) apr_thread_join(apr_status_t *retval, apr_thread_t *th
          */
         if (thd->exitval != -1) {
             *retval = thd->exitval;
+            apr_pool_destroy(thd->pool);
             return APR_SUCCESS;
         } else 
             return ret;
@@ -153,7 +164,12 @@ APR_DECLARE(apr_status_t) apr_thread_join(apr_status_t *retval, apr_thread_t *th
 
 APR_DECLARE(apr_status_t) apr_thread_detach(apr_thread_t *thd)
 {
-	if (suspend_thread(thd->td) == B_NO_ERROR){
+    if (thd->detached) {
+        return APR_EINVAL;
+    }
+
+    if (suspend_thread(thd->td) == B_NO_ERROR) {
+        thd->detached = 1;
         return APR_SUCCESS;
     }
     else {